I would use one capful or 3 tablespoons for a hanging basket that is 14 inches wide. The dose is 3 tablespoons for a 2 gallon container or 4 square feet and I am assuming your hanging basket would hold about 2 gallons of soil. Don\'t worry if you a bit more or a bit less than the recommended amounts of Osmocote. This is a slow release plant food and I have never seen any fertilizer damage from using too much, and I have had great results using a bit less than recommended. Enjoy those begonias, Marianne Binetti